Bjarne Stroustrup, author of The C++ Programming Language

I like my code to be elegant and efficient. The
logic should be straightforward to make it hard
for bugs to hide, the dependencies minimal to
ease maintenance, error handling complete
according to an articulated strategy, and per-
formance close to optimal so as not to tempt
people to make the code messy with unprinci-
pled optimizations. Clean code does one thing
well.

>>6
The key problem is not the existence of templates, its that all Sepples libraries with few exceptions depend on them.
Compilation time skyrockets, debugging becomes much slower and impractical, nested templates interact non-intuitively with classes(concepts and variadic templates); complexity of resulting code is in tens of megabytes.
Templates are much slower to compile than any macros they suppose to replace,
Templates appear even messier than macros(especially explicit template instantiation which is suppose to lead to "Clean Code", since it so transparent,type-safe and readable).
The treachery of C++ is that even if you think you work with template-free code, behind the scenes are thousands of implicit templates being instantiated and specialized.